The present invention relates, generally, to alignment systems for hand-held tools, and, more particularly, to alignment systems for a hand-held tool having an axial bit to be aligned with a workpiece.
It is difficult, especially for amateurs, to align the bit of a hand-held tool with the surface of a workpiece. Usually, the bit is desirably aligned at a 90xc2x0 angle to the planar surface of a workpiece, that is, normal to the surface. Various devices have been produced to assist the user in aligning such a tool, one of which is an appliance comprising a cradle in which an electric drill is clamped. Rods connect the cradle to a plate or annular ring which is held against the workpiece. Usually the plate or ring is at right angles to the axis of the bit of the drill, so that when the plate or ring is urged against the surface of the workpiece, the resultant bore in the workpiece will be normal to the surface plane of the workpiece. In a refinement of such a device, the plate or ring is pivoted so that the bore can be made at an oblique angle to the workpiece. Such prior art devices leave much to be desired. They are cumbersome, and add undesired weight to the drill.
It is an object of the present invention to provide a method and system which permit the bit of a tool to be quickly and accurately aligned with respect to a workpiece, with considerable precision, and without adding significantly to the weight of the tool. This and other objects of the present invention are accomplished by providing a laser beam source mounted on the tool which emits a beam extending forwardly toward a workpiece along a path substantially parallel to the axis of the bit. Reflector means are provided for disposition on the surface of the workpiece at a preselected angle to the workpiece. The reflector means includes a planar mirror in the path of the beam so as to intercept the incident beam and reflect it backwardly therefrom. Detecting means are disposed between the laser beam source and the planar mirror to detect both the incident beam and its reflected beam, and which provide an indication when the beams are coincident. When the beams are coincident, the bit of the toll will be aligned with considerable precision at the preselected angle to the surface of the workpiece.
In my earlier application, Ser. No. 09/760,634, now abandoned a first embodiment of the present invention was disclosed in which the detector means comprises a translucent screen on which an image of the incident beam and an image of the reflected beam are displayed. When both images are coincident on the screen, so too are the beams, and the tool is properly aligned with the respect to workpiece. In another embodiment, the detector means comprises a screen having a central region which permits transmission of the incident beam through the screen, but which is otherwise opaque. The reflected beam creates an image on the side of the screen facing toward the mirror, which image is visible in the mirror. If the incident beam and the reflected beam are coincident, the image of the reflected beam is subsumed in the incident beam, indicating that the tool is properly aligned with the workpiece.
In yet another embodiment, the detector means comprises a photoelectric cell through which the incident beam passes, resulting in the generation of an electrical signal proportional to the energy of the incident beam. If the incident beam and the reflected beam are coincident, the signal generated by the photoelectric cell will be enhanced by the reflected beam, and the resultant enhanced signal may be used to trigger an audible indication that the tool is properly aligned.